An admin makes the switch to see how it really works -- with mixed results

The come-on is enticing: Replace that expensive, high-maintenance Microsoft Exchange platform -- and maybe some of your other Microsoft software -- with Google's Apps Premier service for a low, low price of $50 per user per year.

Google will host your email, calendars, documents, and more in their cloud. You can get at everything through a Web browser using the well-regarded Gmail interface, and you may be able to keep using your own client software, even Outlook. Google promises 99.9 percent uptime, and its support includes telephone access to real people. SSL encryption is required to be on, and Google uses the services of its Postini unit to provide malware protection. Google Apps Premier also supports shared contact lists and more sophisticated contact migration, such as LDAP synchronization.

Sounds good, but can Google Apps Premier really deliver on what businesses need?

Whatever you're paying for Exchange and other Microsoft servers, I guarantee it's more than what Google Apps Premier costs, but that's not the only issue. A major platform change is disruptive, and you may have come to rely on Exchange features that either have no equivalent in Google Apps or will require some conversion work.

This was the quandary I faced for my own small business and personal domain. Only a few people use it, but we all love Outlook and the power we get from our hosted Exchange server at AppRiver. Although I'm very happy with AppRiver and I'm paying a fair price, I need to save some money -- just like a lot of larger companies.

So I gave it a shot. Here's what I found and what you need to know before you make your decision.

Mobile support is equivalentGoogle has a plug-in for BlackBerry Enterprise Server, but it doesn't run BlackBerry Enterprise Server. You'll need to run BES yourself or find a provider that will host it with the plug-in.

When it comes to mobile, you won't save any effort with Google Apps, though you get the same capabilities as you would with Exchange -- including the burden of dealing with BES yourself.

Migration testing is incomplete, slowI have just two real users on my domain, but I made sure to learn and test at least some of the tools for larger organizations. Google has put together a wide variety of options for migrating your email installation from Exchange (and from Lotus Notes, which I did not test) to Google Apps Premier. If you have more than a handful of users, your main migration tool from Exchange will be Google Apps Migration for Microsoft Exchange (GAMME), which performs bulk migrations of users from the Exchange Server to Google Apps through an intermediary system running the migration app.

The Administration Guide for GAMME made a great impression on me. Google has the approach to this exactly right. The guide stresses the importance of pilot migrations and phasing in the actual transfer, and provides extensive guidance for this approach. In fact you'd be nuts to try this without a test migration. Even I did one for my puny domain. Fortunately, you can test Google Apps Premier for free for 30 days.

The tricky part is that you can't change the MX records on your mail domain until you do the real migration. Because the test users won't have their real email domain in their address (otherwise, their email is down while you are testing), testing can be awkward. For example, I had to use the test account larry@larryseltzer.net, but my normal mail comes in to larry@larryseltzer.com. I finessed the mismatch by forwarding larry@larryseltzer.com to larry@larryseltzer.net and using a reply-to on the .net address, but that of course means testing under abnormal conditions.

When it came time to do my actual GAMME migration, parts of it failed, returning errors that Google's support staff wasn't entirely able to explain. On Google's advice, I switched to the command-line version of GAMME to specify particular parameters. It still didn't work quite right, but running it twice migrated all my data.

GAMME is a slow process. As the docs recommend, you want to shut off email for a weekend -- maybe a long weekend -- when running it. You could scale the performance and decrease the total downtime by running multiple GAMME systems to port different groups or users, or perhaps in different virtual machines on the same computer, or even different sessions on a Terminal Server.

For smaller installations or special cases, GAMMO (Google Apps Migration for Microsoft Outlook) migrates a single Outlook user profile from a client to Google Apps. This tool worked flawlessly for me.

You have a choice of email clients -- which you'll appreciate After the migration is complete, you have some choices for how to handle email: You can work in Gmail or you can work in Outlook, using GASMO (Google Apps Sync for Microsoft Outlook). This tool has a pretty bad reputation, but it works surprisingly well for me. Google also supports IMAP.

Half of the users in my installation (that would be my wife) were adamant about keeping Outlook. GASMO is both a local MAPI provider and a tool for creating Outlook profiles for synchronizing the Outlook account with a Google Apps account. There is a slow, one-time process to synchronize the Google Apps mail, contacts, and calendar data with the Outlook equivalents. It took many hours each time I ran it, but the further you get from that initial sync, the faster Outlook feels -- as fast as with Exchange, I'd say.

Folders don't work the way you're used toUnlike most conventional mail clients, Gmail doesn't have hierarchical folders, but instead uses labels. You can work on all messages with a particular label and treat them as if they were in a folder. Labels don't have a hierarchy as such, but a message can have more than one label and thus appear in both label views.

To map labels into Outlook's hierarchical folders, GASMO turns folder locations into fake hierarchical labels: A message in the InfoWorld folder will have a label of Inbox\InfoWorld. This makes it possible for a message to appear in more than one folder in Outlook. If you delete one of the messages, all the instances are deleted, which is not what you'd expect if you're Outlook-oriented.

The messiness of the hierarchical labels could make it difficult to get used to Gmail after a migration; you start getting a lot of backward slashes in label names to simulate folder hierarchy, rather than the clean names of Exchange folders. If you decide you want to use the Gmail interface instead of GASMO, you may find it worthwhile to restructure your labels to the friendlier, folder-style names it supports.

Using the Google interfaces is not an easy adjustmentAt first I wanted to use the Gmail interface, figuring I'd make a clean break with Outlook, but using it wasn't so easy. I missed features in Outlook that are weak or absent in Google Apps, such as Outlook's powerful rules. And the fact that GASMO was working so well for my wife led me to give it a shot; I'm still with it. The Gmail interface can be tolerable for short periods of time when I need it, such as on my Droid smartphone, but it is a chore.

Google Calendar is less capable than ExchangeI had also heard of problems with using the Google Calendar interface when compared with Exchange's and Outlook's. No question about it, Google Calendar is no match for the Microsoft product, but it has been good enough for me so far.

Google Calendar in Google Apps Premier is strong in many areas. It supports resource calendars, such as for conference rooms, but GAMME doesn't migrate them from Exchange. Making multiple calendars and checking them is easy, but Google Calendar lacks many of the complex features for meeting setup, such as optional versus required meeting invites.

One of the biggest Exchange features not supported by Google Apps is Public Folders. As a replacement, you could create a Google Group (basically a Usenet-like newsgroup). They are archived and searchable, but not as well integrated as public folders, especially if you're using Outlook. As an alternative, you can also share any file on Google Docs.

Bear in mind that Google is creating APIs for all its features, so you can write your own apps. And you may be able to find third-party modules for a missing feature in the Google Apps Marketplace.

Google Apps can work differently as time passesUnlike typical Exchange hosting, Google Apps is a dynamic environment. Don't be too surprised if you wake up one morning and some feature operates differently. At one point during my brief test period, the online documentation changed in a way that affected my tests, but it's not clear if the product itself changed.

There are good aspects to this dynamism, but if you treasure stability and being able to test changes before implementing them, Google Apps may be a problem.

Google Apps doesn't play with other Google appsI was surprised to discover that you cannot use your Google Apps login to access Google services not provided in Google Apps, such as Google Reader. The work-around -- to use a regular Google account to access those services -- is not at all satisfying, because you can't log in to more than one Google account at a time in the browser. You realistically have to use one browser for Google Apps and another for other Google services. (Google says it will fix this issue later this year.)

Your compliance needs may or may not be metAs with any hosted service, you may be concerned about the fact that you no longer directly manage potentially sensitive data. Google Apps Premier's Terms of Service agreement (section 1.2) essentially says that Google will guard your data with the same measures and vigilance with which it guards its own. I find this reassuring.

But you or your lawyers may have a problem with the terms' statement: "Google may store and process customer data in the United States or any other country in which Google or its agents maintain facilities." Welcome to the cloud.

Google Apps Premier can replace Exchange, but it's no givenThere's no way around the fact that by migrating from a mature, stable, and well-understood platform like Outlook and Exchange to an evolving newbie like Google Apps, you're a pioneer. You may discover gold in California or ruination in Death Valley based on your combination of needed capabilities, users' adaptability, compliance requirements, and degree of cost savings needed to justify the disruption.

It'll work for me, but I have a really small office. But don't forget if you're tired of managing Exchange yourself, you have the option of hosted Exchange. It will cost more than Google Premier Apps, but it also will maintain familiarity and be less disruptive.